Method of making a cast of a foot or hand



April 5, 1966 M. R. LEVITT 3,244,737

METHOD OF MAKING A CAST OF A FOOT 0R HAND Filed Jan. 12, 1962 INVENTOR. Mz 704/ A? div/77 BY @i mle zms United States Patent 3,244,787 METHOD OF MAKING A CAST OF A F061 0R HAND Milton R. Levitt, New Brunswick, Nl, assignor to The Scholl Mfg. Co., Inc., Chicago, 111., a corporation of New York Filed Jan. 12, 1962, Ser. No. 165,882 6 (Ilaims. (Cl. 264-223) This invention relates to improvements in a method of making a cast or a body extremity such as a foot or hand, the invention being highly desirable for use by physicians, surgeons, chiropodists, odiatrists, orthopedists, as well as others for the production of an accurate cast of a foot or hand, although the invention may have other uses and purposes as will be apparent to one skilled in the art.

In the past, when casts, such as plaster casts, were made of the hands or feet to enable the proper fitting of corrective or surgical appliances and devices or the building of a custom made shoe, plaster of Paris was most frequently utilized to make the mold. Such, obviously, was extremely messy, uncomfortable to the patient, and resulted in at least a two-part mold thus increasing breakage and decreasing accuracy of the ultimate cast. Most recently attempts have been made to cast an extremity by utilizing an alginate compound which sets into an elastic gel from which the extremity may be withdrawn due to the elasticity of the gel so as to provide the mold for the resultant cast. Alginate compounds have proven objectionable, however, because they require an objectionable amount of mixing, a beater being necessary in most cases, they are opaque and the extremity is not visible during the making of the mold, the material must be poured in two stages or steps in the forming of the mold, and an objectionable amount of time is required for the material to set. With the use of alginate compounds the patient was subject to discomfort for substantially as long a time as formerly was required to make a plaster of Paris mold.

With the foregoing in mind, it is an important object of the instant invention to provide a method of making a cast of an extremity such as a foot or hand, in the practice of which the extremity of the patient is in contact with the material forming the mold an exceedingly short time, usually one and two minutes.

Another object of this invention is the provision of a method of casting an extremity, in the practice of which method only a single pouring of the material forming the mold around the extremity is necessary, and the finished mold is one single piece. A further object of this invention is the provision of a method of making a cast of an extremity, including the steps of pouring transparent molding material around the extremity and adjusting the extremity to the desired position, it necessary, as the mold material starts setting.

It is also a feature of this invention to provide a method of making a cast of an extremity, by which method the mold for the cast is made in an extremely short period of time, the patient is put to a minimum of discomfort, and the cast made from the resulting mold is ex tremely accurate.

While some of the more salient features, characteristics and advantages of the instant invention have been above pointed out, others will become apparent from the following disclosures, taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a vertical sectional view through a molding container diagrammatically illustrating an extremity in position for the forming of a mold;

FIGURE 2 is a vertical sectional view through a moldrial to the extremity;

3,244,787 Patented Apr. 5, 1966 FIGURE 3 is a vertical sectional view through the container showing the material set around the extremity, and indicating the freeing of the extremity;

FIGURE 4 is a vertical section through the container diagrammatically showing the pouring of the final cast in the mold cavity; and

FIGURE 5 is a perspective view of the completed cast.

By way of example, the instant invention is diagrammatically illustrated in the drawings in connection with the making of a cast of a human foot, it being understood that the making of a cast of the hand would be accomplished by almost identically the same manner.

The making of a cast in accordance with the instant method requires the use of a molding container 1 of sufficient size to receive the extremity and an adequate amount of mold forming material. The container may be aluminum, glass, plastic, stainless steel or of any other suitable material.

The foot 2, of which a cast is to be made, is first positioned within the container 1, spaced above the bottom of the container as clearly seen in FIGURE l. i If the purpose of the ultimate cast is to enable the fitting of the particular foo-t with a specially made or custom built shoe, the foot is positioned as shown in FIGURE 1 with the heel elevated approximately one-half inch above the ball of the foot. It is a simple proposition for a patient to sit in a chair and maintain the foot in proper position and stationary during the short time required for the making of the mold. .If so desired, although such is not essential, the extremity may be covered with a release coating, such as a spray of silicone compound.

With the foot in position, the molding material is poured into the container preferably from two sources such as separate vessels 3 and 4, as seen in FIGURE 2. In an exceedingly short time, a minute usually being sufficient, the molding material 5 sets into a solid gel of suflicient stiffness to retain its shape, but possessing sufficient elasticity and flexibility as to permit withdrawal of the foot from the material. As soon as the material has set the foot may be withdrawn, and this is preferably accomplished by first stretching the skin around the ankle as indicated at 6 in FIGURE 3 to free the skin from the mold material 5 and provide a passage 7 through which air may enter between the material and the foot. Wiggling of the toes will aid in causing the air to reach the toes, after which the heel is slowly elevated and withdrawn from the set material and the foot is slid out of the set gel which is sufficiently elastic for that purpose, and which immediately assumes its former shape upon removal of the foot, leaving a cavity 8 in the mold.

After the removal of the foot, plaster of Paris or equivalent casting material 9 may be poured from a vessel 10 into the mold cavity 8, and will set therein to form a finished cast 11 of the foot. The cast may be removed from the mold material in any manner, since the mold is usually destroyed after the making of the cast. The practice of this method results in the provision of a cast that is so accurate that the texture of the skin appears in the finished cast.

A highly satisfactory mold material for use in practicing the instant invention embodies a gelling agent, preferably in powder form, and which is a mixture of two organic monomers, acrylamide and N,N'-methylenebisacrylamide, in proportions which produce very stiff gels from dilute aqueous solutions when properly catalyzed. Assuming 100 parts in the gelling agent, the acrylamide preferably comprises between 93 and 97 parts, 95 parts of acrylamide providing a substance that has proven highly satisfactory.

The catalyst system involves two components. The first of these components may be referred to as catalyst DMAPN and consists of beta-dimethylaminopropionitrilel The second component of the catalyst system is ammonium persulfate.

In providing the solution to form the mold, a sufficient amount of water is taken to adequately cover the extremity, which amount naturally depends upon the size of the extremity of which the cast is to be made. For the comfort of the patient, the water is preferably tepid, 25 to 30 C. being satisfactory. The weight of the quantity of water selected is noted, and the gelling agent may be from 3% to 10% of the weight of water, the first catalyst component may be from 0.4 to 0.7% of the weight of the water, and the second catalyst component also O.40.7% of the weight of the water. These proportions are not absolutely critical and variance in the proportions aflects the gelling time. However, it has been found that an extremely rapid setting solution may be provided with the gelling agent at 7 /2 to 8% of the weight of water and each catalyst component approximately 0.5% of the weight of the water.

In order to avoid possible wastage of time, material, and labor, which may be occasioned by some unexpected delay on the part of the patient, it is preferable to mix the solution in two steps. First, in a quantity of the water, say one-half the amount, the gelling agent is thoroughly dissolved and then the first catalyst component DMAPN, is added to that same aqueous solution. At about the same time, but in a separate vessel the second catalyst component, ammonium persulfate is added to the remainder of the water. Gelling will not take place until the second component of the catalyst system is added to the solution containing the gelling agent and first component of the catalyst system. After the patients foot has been positioned properly, both of the aqueous solutions are put into the molding container one after the other or simultaneously, as indicated by the vessels 3 and 4 in FIGURE 2 of the drawing, so that the two solutions intermix. Gelling starts almost immediately and a stitf gel is formed in a matter of seconds. Uf course, the gelling agent and first catalyst component may be mixed in all of the water, and just before this solution is poured into the molding container the second catalyst component may be added, but the two solutions are preferable should the patient unexpectedly cause a delay.

The ultimate solution is substantially transparent, and the foot is visible through the solution so that minor adjustments of the position of the foot may be made immediately upon pouring the solution into the molding container in the event the foot or other extremity becomes slightly out of desired position. During gelation, the patient sufiers no discomfort due to heat, pressure, or otherwise by virtue of the gelation. In a matter of less than two minutes after the solutions have been poured into the molding container, the patients foot or hand may be removed from the set gel in the manner previously described, and the final cast of plaster of Paris or the equivalent may be immediately poured into the cavity of the molding material, if so desired. Within a very few minutes the complete cast is available for examination and use.

From the foregoing it is apparent that I have provided a method of making a cast of an extremity which results in an extremely accurate completed cast in a far shorter period of time than was heretofore possible, with the patient remaining perfectly comfortable at all times and subjected to the molding material for a matter of not over two or three minutes. Only a single pouring operation is necessary, and a one-piece mold results from which the ultimate positive cast of the extremity may immediately 'be made. Not only by virtue of the small amount of time involved is the method extremely economical, but the cost of the materials used is on a comparable basis with the cost of materials heretofore used.

It will be understood that modifications and variations may be efiected without departing from the scope of the novel concepts of the present invention.

I claim as my invention: 1. The method of making a cast of an extremity such as a hand or foot with the aid of a gellable material, including the steps of (a) placing the extremity in a desired position in an empty undivided molding container elevated from the container bottom, (b) filling the container sufficiently to cover the extremity with a transparent gel forming solution, viewing the extremity through the transparent covering solution and finally adjusting the position of the extremity in the setting gel if necessary and then maintaining the extremity stationary until the solution has gelled, (d) sliding the extremity out of the set flexible gel,

and (e) pouring a molding compound into the cavity in the gel. 2. The method of making a mold of an extremity such 20 as a foot or hand for casting purposes, including 3. The method of making a mold of an extremity such a: a hand or foot for casting purposes, including the steps 0).

(a) covering the extremity with a release agent,

(b) positioning the extremity in an empty undivided molding container,

(6) covering the extremity with a substantially trans parent solution settable into an elastically flexible solid,

(d) viewing the extremity through the solution and effecting desired final adjustments and then holding the extremity stationary while the solution sets, and

(e) withdrawing the extremity from the elastically flexible solid.

4. The method of making a mold of a foot for casting purposes from a mixture of organic monomers catalyzed with a catalyst system involving two components both of which must be present to eflfect catalyzing to cause the monomers to set into an elastically flexible gel, includingthe steps of (a) forming an aqueous solution containing the monomers and one component of the catalyst system,

(b) forming an aqueous solution containing the other component of the catalyst system and which on combination with the aqueous solution containing said one component provides an ultimate solution which is substantially transparent and sets rapidly into an elastically flexible gel,

(0) placing the foot in a casting container with the foot elevated above the bottom of the container, (d) pouring both solutions into the container to provide said substantially transparent ultimate solution and to cover the foot to the region of the ankle, (e) viewing the covered foot through the substantially transparent covering solution and making any final adjustments of the foot that may be desirable, (f) maintaining the foot motionless while said ultimate covering solution gels, and (g) sliding the foot out of the set gel. 5. The method or" making a mold of an extremity such as a hand or foot for casting purposes, including the steps of (a) positioning the extremity in a molding container,

the steps' (b) pouring into the container a quantity sufficient to cover the extremity of a substantially transparent solution containing a mixture characterized 'by rapidly setting into an elastically flexible gel which is sufficiently hard to make an accurate plaster cast in a molding cavity formed therein and comprises acrylamide and N,N-methylene-bisacrylamide and ammonium persulfate to catalyze the same,

(c) observing the extremity through the transparent (c) placing the foot in an empty undivided casting and to cover the foot to the region of the ankle,

(e) viewing the covered foot through the transparent covering solution and making any final adjustments of the foot that may be desirable,

(f) then maintaining the foot motionless until said ultimate solution has set into said elastically flexible (g) stretching the skin of the foot adjacent the ankle to allow air to enter between the foot and gel,

liquid mixture and if necessary making any desired 10 (h) wiggling the toes of the foot to allow entering air final adjustments thereof to afiford a preferred posito reach the toes, tioning in the liquid before gelling is completed, WlthdraWlng t f t slowly by first freeing the (d) holding the extremity stationary while said soluheel and sliding the foot out of the elastically flextion sets into a stiff but elastically flexible gel, and 1h16 g i (e) withdrawing the extremity from the set elastically (J) Pohflng a Plaster materlal into the mold cavity 16ft flexible gel, by the foot in the gel, and 6. The method of making a plaster cast of the foot {emOl/ing the finished Cast after the Plaster with the aid of a catalyzed gelling agent, including the thflal has steps of (a) forming an aqueous solution containing a gelling 20 References Clted by the Exammel' agent and one component of a catalyst system, UNITED STATES PATENTS (in) forming an aqueous solution containing the re- 1,404,896 1/1922 Rowley ma mng component of the catalyst system and 2 177,304 10/1939 Murray which on combination with said aqueous solution 2,453,604 11/1948 Tenebaum et aL a ng sand one component provides an ultimate 5 2,487,965 11/1949 Dresser 264 223 soluilonnvhich 1sI substiilntlally btlransparent and sets 2,745,813 5/1955 Logemann et a1. 260 '3 rap. y Into an E 881163 y flexr 6 gel, 2 94 2 7 5 Brindis.

container with the entire foot elevated from the bottom of the container and the heel elevated above 3 the ball of the foot,

((1) pouring both solutions into the container to provide said substantially transparent ultimate solution ALEXANDER H. BRODMERKEL, Primary Examiner. WILLIAM STEPHENSON, Examiner.

C. N. SHANE, I. R. DUNCAN, B. SNYDER,

Assistant Examiners. 

1. THE METHOD OF MAKING A CAST OF AN EXTREMITY SUCH AS A HAND OF FOOT WITH THE AID OF A GELLABLE MATERIAL, INCLUDING THE STEPS OF (A) PLACING THE EXTREMITY IN A DESIRED POSITION IN AN EMPTY UNDIVIDED MOLDING CONTAINER ELEVATED FROM THE CONTAINER BOTTOM, (B) FILLING THE CONTAINER SUFFICIENTLY TO COVER THE EXTREMITY WITH A TRANSPARENT GEL FORMING SOLUTION, (C) VIEWING THE EXTREMITY THROUGH THE TRANSPARENT COVERING SOLUTION AND FINALLY ADJUSTING THE POSITION OF THE EXTREMITY IN THE SETTING GEL IF NECESSARY AND THEN MAINTAINING THE EXTREMITY STATIONARY UNTIL THE SOLUTIN HAS GELLED, (D) SLIDING THE EXTREMITY OUT OF THE SET FLEXIBLE GEL, AND (E) POURING A MOLDING COMPOUND INTO THE CAVITY IN THE GEL. 